Black Knot Fungus

 Black Knot Fungus, is a black lumpy fungus that 

feeds on the branches, eventually disfiguring trees.

This disease can occur on both sweet

and sour cherry,  wild cherries and plum trees.

The disease black knot is caused by the fungus

(Apiosporina morbosa) .

     The Black knot fungus infects trees 

between April and June during warm, 

wet weather. The first symptom is a small, 

light brown swelling on the 

current or last year’s growth. 

These swellings are difficult to notice 

at first until the following spring when 

they enlarge and appear as an 

olive green velvety knot.

During this stage the fungus produces 

spores which are released at or near 

the time the trees are beginning to leaf.

Spore release is heaviest at blossom time. 

Soon after, the knots become darker 

and by fall, they appear as the black

knots that are atypical of the symptoms. 

The disease may not be recognized 

until one or two years after 

the original infection.

Knots will continue to grow until

they girdle the branch and kill it. 

Severe infections can eventually kill the tree.

Many pieces of fungus, -- 

approx. 10 were cut from the tree.

A large knot of fungus

Martin removing some branches.

Showing a large piece of black fungus.

He has a long tool to do the job...

The diseased pieces must be destroyed,

burnt, or put in the garbage.

The same tree in the Spring in flower

Thanks for your visit

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